Laser amplifiers are used to increase the intensity of a laser beam. Devices for amplifying laser beams are known which are formed of multi-stage amplifier systems, in particular. For analyzing the laser beam between each amplifier stage, these devices use additional partially transmitting components, as e.g. partially transmitting mirrors.
But using these partially transmitting mirrors means that additional elements have to be provided. Due to the use of additional elements, construction becomes more costly and additional space may be necessary.
Moreover, due to the partial transmission of the mirrors, it may be difficult to cool down the back of the mirrors.
However, when using a laser beam, it is also possible that beams travel in the reverse direction with respect to the propagating direction of the laser beam. These reverse beams can occur due to “self-lasing” or reflections of a forward-propagating beam upon elements of the laser system or, when exposing a target to the laser beam, due to reflections from this target. In order to analyze these reverse beams using conventional techniques, for example further partially transmitting mirrors may be necessary.